Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Electromagnet not repelling neodymium magnet

  1. Mar 15, 2014 #1
    Hello this is my first time to post.
    I have an electromagnet powered by a car battery charger set at 12 volts the problem is I can't get the electromagnet to repel the neodymium magnet. I have tried switching around the positive and negative leads of the power supply and switching the side of the magnet that is facing the electromagnet. The electromagnet will pick up a wire strippers yet it wont repel a magnet. So I'm just wondering does anyone know what I'm doing wrong.
    Last edited: Mar 15, 2014
  2. jcsd
  3. Mar 15, 2014 #2


    User Avatar
    Science Advisor

    The magnet will be attracted to the iron of the electromagnet and will not be repelled unless you can generate enough magnetic field from the current in the coil.

    So, you may need more turns of wire on your electromagnet or more current in it, or both.
  4. Mar 16, 2014 #3
    Ok thanks I'll try that.
  5. Mar 16, 2014 #4


    User Avatar
    Science Advisor

    OK, but don't expect too much success.

    The very powerful Neodymium magnet induces a strong magnet in the soft iron of the electro magnet. This magnet has a polarity such that it attracts the Neodymium magnet.

    To repel the Neodymium magnet, you would need to produce a stronger magnet of opposite polarity with the electromagnet.

    Unless it is very efficient, I don't think you will be able to do this.

    A very effective way of testing this is to tape the magnet to the pan of a digital scale ( weighing device) with one pole pointing upwards, and mount the electro magnet above it, but not close enough that they move towards each other.

    Note the weight of the magnet, then apply current to the electro magnet and note the change in weight of the magnet.

    With one direction of current, the electromagnet will increase the attraction of the magnet (and reduce the weight reading on the scale) and in the other direction of current, there will be an increase in weight due to repulsion.
  6. Mar 17, 2014 #5
    I'll try that
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook